VA Morning Report 12.5.17: Syncope, hypoglycemia, and aortic dissection potpourri

Case summary: Thanks to the incomparable Matt Schwede, who presented the case of a 64M with PMH back pain, dermatitis NOS, current EtOH and prior heroin/meth/cocaine abuse, who presented with syncope and hypoglycemia, as well as chest pain radiating to the back and was found to have a troponin of 15 and high-grade LAD lesion on LHC.

Top pearls:

  1. Hypoglycemic unawareness occurs most commonly in patients with long-standing DMT1 or 2 on insulin; it is more common in those with recently improved glycemic control and is often precipitated by recurrent iatrogenic hypoglycemia.
  2. Other medications and conditions can blunt or mask hypoglycemic awareness, including beta blockers and sedating medications.
  3. A unifying diagnosis for aortic dissection and elevated troponin is dissection of the R coronary artery leading to EKG evidence of inferior MI.

 

Etiologies of reduced hypoglycemic awareness

  • Recall the tragic death of Julia Roberts’s character in Fried Green Tomatoes!
  • A reminder about Whipple’s triad:
    • symptoms consistent with hypoglycemia
    • low plasma glucose
    • relief with glucose administration
  • Symptoms: usually idiosyncratic, but patients learn to detect their own unique flavor
    • Neurogenic/autonomic- palpitations, tremor, hunger, sweating
    • Neuroglycopenic- behavioral changes, slowed cognition, seizure, coma, death
  • What causes reduced hypoglycemic awareness?
    • Iatrogenic antecedent hypoglycemia causes a) reduced counter regulatory mechanisms (e.g. epinephrine, which triggers glycogenolysis) and b) reduced sympathoadrenal response, which normally generates the sympathetic physiologic symptoms (e.g. palpitations, tremors).
      • Sleep and exercise can also impair these pathways (both affect catecholamines, cortisol).
      • Studies have shown that even 1-2 weeks of avoiding hypoglycemic episodes can restore hypoglycemic awareness.
      • Risk factors: duration of disease and improved metabolic control
    • Beta blockade, alpha blockade, other sedating medications can also impact patients’ ability to recognize the autonomic/neuroglycopenic symptoms
    • Finally, ganglionic blockade, cervical cord injury, and sympathectomy blunt the physiologic response!

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4499525/

Aortic dissection pearls

  • This patient described his chest pain as radiating to the back, which was initially concerning for aortic dissection.
  • Is D-dimer useful in the diagnosis of acute aortic dissection?
    • CT and MRI are 100% sensitive and 95-10)% specific for diagnosis
    • TEE is 86-100% sensitive
    • D-dimer is 51.7-100% sensitive; some commentators have concluded that it is NOT useful because it would only reliably rule out low-risk patients, which would not include most patients in whom you’re suspecting aortic dissection (e.g. with chest pain)
  • We discussed the common complications of aortic dissection:
    • Coronary ischemia secondary to coronary dissection-
      • most commonly the R coronary (with EKG showing inferior MI)
      • Goop made the astute point that L coronary involvement may lead to out-of-hospital death and thus may be under-reported in case series!
    • aortic rupture
    • tamponade
    • stroke
    • visceral ischemia
    • circulatory collapse

Two great reviews of aortic dissection here and here.

 

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